This application relates to a compressor for a gas turbine engine, wherein the stator vanes are asymmetric, and wherein acoustic cutoff is achieved.
Gas turbine engines typically include a compressor which compresses air and delivers it into a combustion chamber. The compressed air is mixed with fuel and combusted in the combustion section. Products of this combustion pass downstream over turbine rotors.
The compressor is typically provided with rotating blades, and stator vanes adjacent to the blades. The stator vanes control the flow of the air to the compressor rotor.
A concept known as “cutoff” is utilized in the design of compressors, and relates the number of vanes in the stator to the number of blades in the rotor. The goal of “cutoff” is to ensure that generated noise decays in a compressor duct, instead of propagating to a far field. Compressors which have achieved cutoff in the past have equally spaced stator vanes across the entire circumference of the stator section, and equally spaced rotor blades.
Recently, asymmetric stator vanes have been developed, which have unequally spaced stator vanes on two halves of a circumference. The spacing of the stator vanes in a lower half is unequal from the spacing of the vanes in an upper half. The purpose of the unequal spacing is structural.